Schismatrix by Bruce Sterling

The main character, Abélard Lindsay, is born in the ancient lunar colony Mare Serenitatis Circumlunar Corporate Republic, into a family of aristocratic Mechanists, but after being sent to the Shaper’s Ring Council, he receives specialized and experimental diplomatic training and gives his loyalty to the Shapers' cause. He, his best friend and fellow Shaper protege Philip Constantine and the beautiful and passionate Preservationist Vera Kelland lead an insurgency against the rulers of the republic, who use Mechanist technology to prolong their lives. The three of them influence the younger generation towards the Shapers' cause in their pursuit of Preservationism, a movement devoted to the preservation of earth-bound human culture. Kelland and Lindsay agree to kill themselves as a political statement, but Lindsay reneges on his suicide pact after Kelland is dead. Constantine attempts to kill Lindsay but instead kills a Mechanist, creating a scandal.